In control systems engineering, what two principal methods are available to implement electronic continuous control loops?

Introduction / Context:
Continuous control adjusts an actuator smoothly in response to measured error between a setpoint and process variable. Engineers can realize these loops with analog electronics or digitally with sampled-data controllers running in microcontrollers, PLCs, or DCS platforms. Understanding both realizations is essential for selecting hardware, designing filters, and meeting performance and cost targets.

Given Data / Assumptions:

• The question asks specifically about electronic continuous control.
• We compare common implementation styles used in modern practice.
• Mechanical or pneumatic systems exist but are not strictly electronic control implementations.

Concept / Approach:
Analog control uses op-amps, resistors, capacitors, and sometimes analog multipliers to implement PID and filters continuously in time. Digital control samples signals via ADCs, computes control laws in software (for example, PID, state-feedback), and outputs via DACs or PWM to actuators. Both can achieve high performance; trade-offs include noise susceptibility, flexibility, ease of tuning, and component drift.

Step-by-Step Solution:

Verification / Alternative check:
Industrial controllers evolved from analog panels to digital PLCs and DCS; both remain in use depending on legacy constraints and application needs.

Why Other Options Are Wrong:

Common Pitfalls:
Ignoring sampling effects and quantization in digital control; overlooking drift and temperature coefficients in analog control.

Final Answer:
Analog and digital.